Hard Disk is Not Detecting

We have IBM eServer x-series -336 which has two hard disks of 300 GB. Both are controlled by RAID controller (hardware based). Out of these two disks, one hard disk is not detecting through Server RAID software. We have tried to detect it through IBM Server guide during windows re-installation but this hard disk is not detecting and when we try to identify both hard disks through Server guide, it gives us only one hard disk as online while remaining hard disk has red icon on it and gives us detail as dysfunction of said hard disk.

Where can I check SCSI IDs at each drive and how can I check termination of SCSI bus? Also these is RAID-1 configured (hardware based) as both are mirror of each other. Please specify procedure in detail.

Check to insure the SCSI ID of the disk (usually done with pins on the disk itself) is not set to the same settings on the other disk.
Then check that it is not set to the DVD-CD settings of either 7 or 15 depending if you have extended SCSI on your IBM server.

Out of the box IBM hard drives usually come with the same Pin settings and therefore would have the same hardware SCSI ID.
You have to find where the jumpers are on the hard drive and what the settings are to insure you are not setting both with SCSI ID 0.

But I have tried to remove online drive and check whether system will boot through mirror harddisk or not, but system could not start through mirror harddisk. Also there is an orange light is coming in front light portion of harddisk.

Prior to this error, both harddisks were properly detected. How can it be possible that SCSI IDs had automatically changed now? I also readout at Tech Data sites that there is no need about jumper settings in IBM SCSI drives during removal ,installation as they are hot swapable drives.

By using raid 1, both the disks are mirrored and having redundancy. your
both disks are working on bay 0 and bay 1.

Because raid 1 depends on two disks. So ist disk has capacity of 300 gb
and other also have the same capacity.

It's going to show you as 150 gb + 150 gb = 300 gb and in disk management it's
showing you as C drive only with the capacity of around 279 gb. If you are
looking on the same thing in your server this means your disks are
mirrored.

If the Hard disks are Hot swap, they are connected to back plane and SCSI ID is managed by back plane. You need to download Serveraid Support CD from IBM site and boot from it. It will give you the failed hard disk location.

from what I have read on the forum one of your drives is just dead.
If the hardware is set for hot swappable and SCSID's are detected rather than set then pull the good one out and see if the other boots.
If it does not then replace it and put the good one back in to rebuild your RAID Mirror.

If your server is set up with Hardware RAID the OS will not see a disk with space but a logical drive that is the mirror. You will see the listing of two disks but only get the space of the mirror or the size of the smallest drive.

Prior to this error, both harddisks were properly detected. How can it be possible that SCSI IDs had automatically changed now? I also readout at Tech Data sites that there is no need about jumper settings in IBM SCSI drives during removal ,installation as they are hot swapable drives.

I have already using IBM Server RAID support bootable CD who shows one harddisk as online and other harddisk as defunct and red icon is present on it. When I try to use option in Action button and click on "Identify harddisks" then green light blinks on both harddisk and space also shows as 279 GB in each hardisk but one harddisk remains as defunct while other harddisk shows as online.

Have you tried pulling the power cords out and letting it drain out for a minute. Also if you know that you have a good drive try to change the defunct conditon and rescan or whatever options you have and reseat the drive while you do this and try this a few times.

I have tried to power off the whole system and pulled out power cord, then I pulled out both harddisks quite some time and then reseated but result is same. I also tried to interchange these harddisks (means where first harddisk was seated, I changed its place and seated on second drive and vice versa), but result is same.

It is simple. Drive failure. Dispose of the drive via an electronics recycler who will destroy it, if the data is sensitive ... then purchase a replacement. If this is not a RAID1, then you need to go to a data recovery. Be prepared to spend $500 - $1000.